U.S. patent number 7,849,879 [Application Number 11/843,687] was granted by the patent office on 2010-12-14 for powder paint recirculation block assembly.
This patent grant is currently assigned to GM Global Technology Operations, Inc.. Invention is credited to Eric G. Norrmalm, Frank P. Rauch, Gunnar Van Der Steur, Fei Yang.
United States Patent |
7,849,879 |
Rauch , et al. |
December 14, 2010 |
Powder paint recirculation block assembly
Abstract
A powder paint recirculation block assembly for use in a powder
paint transfer assembly, and a method of operation, is disclosed.
The recirculation block assembly includes a powder paint
recirculation block body having an intake flow passage directing
flow to an applicator flow passage leading to an application flow
control assembly and a return flow passage leading to a return flow
control assembly. The angles (change in direction) through which
powder paint flows may be minimized to minimize potential impact
fusion. The pinch rubbers in pneumatic pinch valves of the
application flow control assembly and return flow control assembly
may be removable to allow for valve repair.
Inventors: |
Rauch; Frank P. (Wyandotte,
MI), Norrmalm; Eric G. (Brooklin, CA), Yang;
Fei (Oshawa, CA), Van Der Steur; Gunnar
(Chesapeake City, MD) |
Assignee: |
GM Global Technology Operations,
Inc. (Detroit, MI)
|
Family
ID: |
40381246 |
Appl.
No.: |
11/843,687 |
Filed: |
August 23, 2007 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20090050709 A1 |
Feb 26, 2009 |
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Current U.S.
Class: |
137/625.47;
210/284; 118/312; 137/625.11 |
Current CPC
Class: |
B05B
7/1468 (20130101); B05B 7/1404 (20130101); Y10T
137/86501 (20150401); Y10T 137/86871 (20150401); Y10T
137/85954 (20150401) |
Current International
Class: |
F16K
11/20 (20060101) |
Field of
Search: |
;137/580,625.11,625.16,625.19,625.47 ;210/278,284,290,676
;118/312 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Fox; John
Claims
What is claimed is:
1. A powder paint recirculation block assembly for use in a powder
paint transfer assembly comprising: a powder paint recirculation
block body having an intake end and an outlet end, and including an
intake flow passage, an applicator flow passage, and a return flow
passage, the intake flow passage extending from the intake end to
the applicator flow passage and the return flow passage, the
applicator flow passage extending from the intake flow passage at a
first angle that is less than forty five degrees toward the outlet
end, and the return flow passage extending from the intake flow
passage at a second angle that is less than forty five degrees
toward the outlet end; an application flow control assembly mounted
to the recirculation block body and including a first pinch valve
assembly in operative alignment with the applicator flow passage
and operative to selectively prevent powder paint flow through the
applicator flow passage; and a return flow control assembly mounted
to the recirculation block body and including a second pinch valve
assembly in operative alignment with the return flow passage and
operative to selectively prevent powder paint flow through the
return flow passage.
2. The powder paint recirculation block assembly of claim 1 wherein
the first angle from which the applicator flow passage extends from
the intake flow passage is less than twenty-five degrees and the
second angle from which the return flow passage extends from the
intake flow passage is less than twenty-five degrees.
3. The powder paint recirculation block assembly of claim 1 wherein
the recirculation block body is made of
polytetrafluoroethylene.
4. The powder paint recirculation block assembly of claim 1 wherein
one of the first and second pinch valve assemblies includes a first
pinch valve body that is threadably removable from the
recirculation block body and a first pinch rubber that is removable
from the first pinch valve body when the first pinch valve body is
threadably removed from the recirculation block body.
5. The powder paint recirculation block assembly of claim 4 wherein
the other of the first and second pinch valve assemblies includes a
second pinch valve body that is threadably removable from the
recirculation block body and a second pinch rubber that is
removable from the second pinch valve body when the second pinch
valve body is threadably removed from the recirculation block
body.
6. The powder paint recirculation block assembly of claim 1 wherein
the return flow control assembly includes an angled connector
mounted on the second pinch valve assembly, the angled connector
including a passage therethrough having a redirection angle of less
than forty-five degrees, whereby when powder paint flows through
the passage, a change in direction of flow is less than forty five
degrees, the angled connector also including a purge air check
valve fitting in fluid communication with the passage.
7. A powder paint recirculation block assembly for use in a powder
paint transfer assembly comprising: a powder paint recirculation
block body having an intake end and an outlet end, and including an
intake flow passage, an applicator flow passage, and a return flow
passage, the intake flow passage extending from the intake end to
the applicator flow passage and the return flow passage, the
applicator flow passage extending from the intake flow passage at a
first angle, and the return flow passage extending from the intake
flow passage at a second angle toward the outlet end; an
application flow control assembly mounted to the recirculation
block body and including a first pinch valve assembly in operative
alignment with the applicator flow passage and operative to
selectively prevent powder paint flow through the applicator flow
passage; and a return flow control assembly mounted to the
recirculation block body and including a second pinch valve
assembly in operative alignment with the return flow passage and
operative to selectively prevent powder paint flow through the
return flow passage, and wherein one of the first and second pinch
valve assemblies includes a first pinch valve body that is
threadably removable from the recirculation block body and a first
pinch rubber that is removable from the first pinch valve body when
the first pinch valve body is threadably removed from the
recirculation block body.
8. The powder paint recirculation block assembly of claim 7 wherein
the other of the first and second pinch valve assemblies includes a
second pinch valve body that is threadably removable from the
recirculation block body and a second pinch rubber that is
removable from the second pinch valve body when the second pinch
valve body is threadably removed from the recirculation block
body.
9. The powder paint recirculation block assembly of claim 7 wherein
the first angle from which the applicator flow passage extends from
the intake flow passage is less than twenty-five degrees and the
second angle from which the return flow passage extends from the
intake flow passage is less than twenty-five degrees.
10. The powder paint recirculation block assembly of claim 7
wherein the return flow control assembly includes an angled
connector mounted on the second pinch valve assembly, the angled
connector including a passage therethrough having a redirection
angle of less than forty-five degrees, whereby when powder paint
flows through the passage, a change in direction of flow is less
than forty-five degrees, the angled connector also including a
purge air check valve fitting in fluid communication with the
passage.
11. The powder paint recirculation block assembly of claim 7
wherein the recirculation block body is made of
polytetrafluoroethylene.
12. The powder paint recirculation block assembly of claim 7
wherein one of the application flow control and return flow control
assemblies includes a first purge air ring mounted in the
recirculation block body and including a first conical passage
extending therethrough.
13. The powder paint recirculation block assembly of claim 12
wherein the other of the application flow control and return flow
control assemblies includes a second purge air ring mounted in the
recirculation block body and including second conical passage
extending therethrough.
14. The powder paint recirculation block assembly of claim 7
wherein one of the first and second pinch valve assemblies includes
a first pinch valve collar mounted around the first pinch valve
body.
15. A method of selectively directing powder paint to a powder
paint applicator and a source hopper, the method comprising the
steps of: (a) directing a flow of the powder paint into an intake
flow passage extending into a powder paint recirculation block
body; (b) closing a first pinch valve assembly in a return flow
control assembly while directing the flow through a second open
pinch valve assembly in an application flow control assembly to
thereby cause the flow of the powder paint from the intake passage
through an applicator flow passage that redirects the flow of the
powder paint at a first angle that is less than forty five degrees;
(c) closing the second pinch valve assembly while opening the first
pinch valve assembly to thereby cause the flow of the powder paint
from the intake passage through a return flow passage that
redirects the flow of the powder paint at a second angle that is
less than forty-five degrees; (d) directing the powder paint from
the open first pinch valve assembly into the source hopper; and (e)
directing the powder paint from the open second pinch valve
assembly to the powder paint applicator.
16. The method of claim 15 wherein step (b) is further defined by
the first angle being less than twenty-five degrees.
17. The method of claim 15 wherein step (c) is further defined by
the second angle being less than twenty-five degrees.
Description
BACKGROUND OF INVENTION
The present invention relates generally to a powder paint transfer
assembly, and more particularly to a powder paint recirculation
block assembly for use in the powder paint transfer assembly.
Paint application systems, such as those for painting vehicle
bodies, may include recirculation valve assemblies that selectively
direct the paint either to a paint applicator or back to the supply
of paint. Some of these paint application systems are used
specifically for the application of powder paint to the vehicle
bodies. A problem that has arisen in the paint application systems
for powder paint is that the recirculation valve assemblies include
flow direction changes at relatively large angles. These large
angles of flow direction change do not work well with powder paint.
This is because the large angles of flow direction change are
believed to cause impact fusion to occur--impact fusion is believed
to be caused when powder paint particles impact together causing
heat, which then fuses the particles together. The fused powder
paint, then, eventually closes off the flow passages, requiring the
painting operations to stop while eliminating these clogs.
Another problem that has arisen in the paint application systems
for powder paint is that some of the recirculation valve assemblies
include pinch valves, and the pinch valves do not have serviceable
components. As a result, when the assembly is cleaned (after
painting) the membranes of the pinch rubbers wear, which eventually
leads to failure of the rubbers. Since the pinch valves do not have
individual serviceable components, the entire valve assembly must
be replaced when the membranes are worn out. This results in much
higher maintenance cost than is desirable.
Thus, it is desirable to have a powder paint recirculation block
assembly for use in a powder paint transfer assembly that overcomes
the drawbacks of the prior art.
SUMMARY OF INVENTION
An embodiment contemplates a powder paint recirculation block
assembly for use in a powder paint transfer assembly. The
recirculation block assembly may comprise a powder paint
recirculation block body, an application flow control assembly and
a return flow control assembly. The powder paint recirculation
block body may have an intake end and an outlet end, and include an
intake flow passage, an applicator flow passage, and a return flow
passage, the intake flow passage extending from the intake end to
the applicator flow passage and the return flow passage, the
applicator flow passage extending from the intake flow passage at a
first angle that is less than forty-five degrees toward the outlet
end, and the return flow passage extending from the intake flow
passage at a second angle that is less than forty-five degrees
toward the outlet end. The application flow control assembly may be
mounted to the recirculation block body and include a first pinch
valve assembly in operative alignment with the applicator flow
passage and operative to selectively prevent powder paint flow
through the applicator flow passage. The return flow control
assembly may be mounted to the recirculation block body and include
a second pinch valve assembly in operative alignment with the
return flow passage and operative to selectively prevent powder
paint flow through the return flow passage.
An embodiment contemplates a powder paint recirculation block
assembly for use in a powder paint transfer assembly. The
recirculation block assembly may comprise a powder paint
recirculation block body, an application flow control assembly and
a return flow control assembly. The powder paint recirculation
block body may have an intake end and an outlet end, and include an
intake flow passage, an applicator flow passage, and a return flow
passage, the intake flow passage extending from the intake end to
the applicator flow passage and the return flow passage, the
applicator flow passage extending from the intake flow passage at a
first angle, and the return flow passage extending from the intake
flow passage at a second angle toward the outlet end. The
application flow control assembly may be mounted to the
recirculation block body and include a first pinch valve assembly
in operative alignment with the applicator flow passage and
operative to selectively prevent powder paint flow through the
applicator flow passage. The return flow control assembly may be
mounted to the recirculation block body and include a second pinch
valve assembly in operative alignment with the return flow passage
and operative to selectively prevent powder paint flow through the
return flow passage; wherein one of the first and second pinch
valve assemblies includes a first pinch valve body that is
threadably removable from the recirculation block body and a first
pinch rubber that is removable from the first pinch valve body when
the first pinch valve body is threadably removed from the
recirculation block body.
An embodiment contemplates a method of selectively directing powder
paint to a powder paint applicator and a source hopper, the method
comprising the steps of: directing a flow of the powder paint into
an intake flow passage extending into a powder paint recirculation
block body; closing a first pinch valve assembly in a return flow
control assembly while directing the flow through a second open
pinch valve assembly in an application flow control assembly to
thereby cause the flow of the powder paint from the intake passage
through an applicator flow passage that redirects the flow of the
powder paint at a first angle that is less than forty-five degrees;
closing the second pinch valve assembly while opening the first
pinch valve assembly to thereby cause the flow of the powder paint
from the intake passage through a return flow passage that
redirects the flow of the powder paint at a second angle that is
less than forty-five degrees; directing the powder paint from the
open first pinch valve assembly into the source hopper; and
directing the powder paint from the open second pinch valve
assembly to the powder paint applicator.
An advantage of an embodiment is that the relatively small angles
for the change of directions for flow of powder paint in the powder
paint recirculation block assembly avoid the potential powder paint
plugging issues in the interior passages.
An advantage of an embodiment is that the pinch rubbers of the
pinch valve assemblies are serviceable, thus reducing costs by
avoiding the need to purchase entire new assemblies when the
rubbers need replacement.
An advantage of an embodiment is that a recirculation block body
made of polytetrafluoroethylene (PTFE) provides for desirable flow
of the powder paint through the passages of the block body.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a perspective view of a powder paint recirculation block
assembly.
FIG. 2 is a plan view, on an enlarged scale, of the powder paint
recirculation block assembly of FIG. 1.
FIG. 3 is a view of the powder paint recirculation block assembly
looking in the direction of arrows 3-3 in FIG. 2.
FIG. 4 is a section view, taken along lines 4-4 in FIG. 3.
FIG. 5 is a partially exploded, perspective view, of a portion of
the powder paint recirculation block assembly, with one purge air
ring and one pinch rubber rotated to provide end views of those
components.
FIG. 6 is a block diagram of the powder paint recirculation block
assembly of FIGS. 1-5 assembled into a portion of a powder paint
transfer assembly.
DETAILED DESCRIPTION
Referring now to FIGS. 1-5, a powder paint recirculation block
assembly, indicated generally at 20, is shown. This assembly 20 may
also be referred to as a selector valve assembly since it
selectively directs powdered paint through the assembly toward a
paint applicator (shown in FIG. 6) or back to a source hopper
(shown in FIG. 6) for the powder paint.
The block assembly 20 includes a powder paint recirculation block
body 22 that is preferably made of polytetrafluoroethylene (PTFE),
which has superior characteristics for powder paint flow. The block
body 22 includes an intake flow passage 24 the intake flow passage
24 extends from an intake end 26 of the block body 22 to a junction
connects with both an applicator flow passage 28 and a return flow
passage 30. The upstream end of the intake flow passage 24 may have
a push lock fitting 31 mounted therein. The passages 24, 28, 30 may
be drilled from a solid PTFE block, if so desired. The applicator
flow passage 28 and return flow passage 30 diverge as they extend
toward an outlet end 32 of the block body 22. The angles 34, 36
(shown in FIG. 4) at which the applicator flow passage 28 and
return flow passage 32, respectively, extend relative to the
direction of the intake flow passage 24 are preferably less than
about forty-five degrees, and more particularly less than about
twenty-five degrees. These small angles 34, 36 help to assure that
the change in direction of the powder paint flow will not cause
impact fusion to occur, thus avoiding clogging of the flow
passages. The block body 22 also includes a pair of mounting holes
38 for securing the block body 22 to a mounting surface (not shown)
during paint operations.
The applicator flow passage 28 directs powder paint toward an
application flow control assembly 40. The application flow control
assembly 40 includes a purge air ring 42 having a conical shaped
passage 44 directing powder paint into a pneumatic pinch valve
assembly 46. The pinch valve assembly 46 includes a pinch rubber 48
that is removably mounted in a pinch valve body 50, a pinch valve
collar 52 that mounts around the pinch valve body 50, and a
pneumatic fitting 54 for connecting to a source of pressurized air.
A compression fitting 56 mounts to the pinch valve body 50 and
includes a passage 58 that defines an outlet 60.
The pinch valve assembly 46 may be assembled by inserting the pinch
rubber 48 and purge air ring 42 into a cavity 62 in the pinch valve
body 50 and sliding the pinch valve collar 52 over the outside of
the pinch valve body 50. External threads 64 on an upstream end of
the pinch valve body 50 may then be screwed into the block body 22,
trapping and thus retaining the assembled components in proper
alignment. The fitting 54 is mounted to the collar 52 and the
compression fitting 56 is mounted to the pinch valve body 50.
Accordingly, the pinch valve assembly 46 can be relatively easily
and quickly disassembled when replacement of a worn pinch rubber 48
is needed. O-rings and seals (not numbered) may be employed as
desired to seal the assembly.
The return flow passage 30 directs powder paint toward a return
flow control assembly 66. The return flow control assembly 66
includes a purge air ring 68 having a conical shaped passage 70
directing powder paint into a pneumatic pinch valve assembly 72.
The pinch valve assembly 72 includes a pinch rubber 74 that is
removably mounted in a pinch valve body 76, a pinch valve collar 78
that mounts around the pinch valve body 76, and a pneumatic fitting
80 for connecting to a source of pressurized air. And angled
connector 82 mounts to the pinch valve body 70 and includes a
passage 84 that defines an outlet 86. The downstream end of the
passage 84, may have a push lock fitting 87 mounted thereon.
Preferably, the change in direction of the passage 84 (angle 94) is
less than about forty-five degrees in order to minimize the risk
that the powder paint will undergo impact fusion as it flows
through the angled connector 82. The angled connector 82 also
includes a check valve fitting 88 that connects to the passage 84
and can selectively direct air toward the outlet 86.
The pinch valve assembly 72 may be assembled by inserting the pinch
rubber 74 and purge air ring 68 into a cavity 90 in the pinch valve
body 76 and sliding the pinch valve collar 78 over the outside of
the pinch valve body 76. External threads 92 on an upstream end of
the pinch valve body 76 may then be screwed into the block body 22,
trapping and thus retaining the assembled components in proper
alignment. The fitting 80 is mounted to the collar 78 and the
angled connector 82 is mounted to the pinch valve body 76.
Accordingly, the pinch valve assembly 72 can be relatively easily
and quickly disassembled when replacement of a worn pinch rubber 74
is needed. O-rings and seals (not numbered) may be employed as
desired to seal the assembly.
FIG. 6 is a block diagram illustrating a simplified version of a
powder paint transfer assembly 100 employing the powder paint
recirculation block assembly 20. In FIG. 6, the solid lines leading
between blocks represent lines through which powder paint flows,
dashed lines between blocks represent pressurized air lines, and
phantom lines between blocks represent electrical connections.
A source hopper 102 is connected to a powder paint source line 104,
which connects at its downstream end to the push lock fitting 31
(shown in FIG. 4) at the intake end 26 of the block assembly 20.
The downstream end of the application flow control assembly 40
leads to a powder paint line 106, which directs powder paint
ultimately to an applicator 108. The downstream end of the return
flow control assembly 66 leads to a powder paint return line 110,
which directs powder paint back two the source hopper 102.
A first pinch valve line 112 extends between the application flow
control assembly 40 and a first solenoid valve 114, a second pinch
valve line 116 extends between the return flow control assembly 66
and a second solenoid valve 117, and a purge air line 118 extends
between the angled connector 82 and a third solenoid valve 120. All
three solenoid valves 114, 117, 120 connect to pressurized air
lines 122 leading to a source of pressurized air 124. A controller
126 connects to and controls the solenoid valves 114, 117, 120, via
electrical connections 128.
The operation of the powder paint recirculation block assembly 20
in the powder paint transfer assembly 100, as shown in FIGS. 1-6,
will now be discussed. As powder paint is fed from the source
hopper 102 through the powder paint source line 104, it enters the
intake flow passage 24 of the block body 22. The controller 126
selectively controls the first solenoid valve 114 in coordination
the second solenoid valve 117 to selectively apply air pressure to
the pinch valve assemblies 46, 72. If the pneumatic pressure is
applied to the second solenoid valve 117, but not the first
solenoid valve 114, the flow of powder paint is directed into the
powder paint line 106 leading to the applicator 108 and blocked
from flowing into the powder paint return line 110. If the
controller 126 reverses the solenoid valves 114, 117, then the flow
into powder paint line 106 is blocked while flow into the return
line 110 is allowed. The relatively small angles used to change the
direction of flow of the powder paint through the block body 22 and
the PTFE material allow for desirable powder paint flow
characteristics. The potential for friction, heat and resulting
impact fusion are minimized as the powder paint flows through the
block assembly 20, thus reducing the risk of powder paint plugging
concerns.
In addition, the powder paint return line 110 can be purged of
powder paint. With the second solenoid valve 117 allowing pneumatic
pressure to close the pinch valve 72 and the first solenoid valve
114 eliminating the pneumatic pressure from the pinch valve 46, the
controller 126 actuates the third solenoid valve 120 to create a
pneumatic pressure in the angled connector 82 via the check valve
fitting 88. The compressed air entering the angled connector 82
will purge the powder paint from the powder paint return line 110,
sending it back to the source hopper 102.
As periodic cleaning of the powder paint recirculation block
assembly 20 occurs, the pinch rubbers 48, 74 wear, which can
eventually leads to failure of the pinch rubbers 48, 74. When
sufficiently worn, the pinch valve assembles 46, 72 can be
disassembled from the block body 22, and the old pinch rubbers 48,
74 can be removed and replaced. The rest of the pinch valve
assemblies 47, 72 and the block body 22 can be reused.
Consequently, the maintenance cost for the block assembly 20 can be
relatively low.
While certain embodiments of the present invention have been
described in detail, those familiar with the art to which this
invention relates will recognize various alternative designs and
embodiments for practicing the invention as defined by the
following claims.
* * * * *